Note: Descriptions are shown in the official language in which they were submitted.
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1 CONTROL APPARATUS AN~ ~ETHOD FOR INDUSTRIAL ROBOT
~A~ r n~ lnv~ o~
The present invention relates to an apparatus for
controlling an industrial robot.
- Japanese Laid-Open Patenf Publication
No. 52-143661 describes a "Method of Controlling an
Industrial Robot". According to the disclosed method,
positional. errors in an operating pattern are stored
as positional difference values, the stored data is
compaxed with basic position data, and an operational
position is corrected on the basis of the difference.
With such a control method, a teaching unit and a
driver unit are integrally incorporated in a control
apparatus, which makes the apparatus unavoidably large
in size. Since corrective arithmetic operations must
be effected for each operational stroke, the
correcting program is nPcessarily lengthy and complex.
If a large number of corrections need to be made, the
- .resulting large number of corxective arithmetic
operations causes the industrial robot to have a low
speed of movement. Also, this arrangement is
disadvantageous in that each robot must be provided
with ~ dedicated control apparatus, and the control
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1 apparatus mus-~ have all of functions necessary to
operate the industrial xobot.
:[n an improvement on ~that method, control of an
industrial robot has been eff~cted by a robot control
unit and a separate programming unit. Each industrial
robot is provided with a dedicated robot control unit,
while a single programming unit, used as an external
teaching device, is shared by a plurality of
industxial robots. The use of the single proyramming
unit as an external teaching device is effective in
practice as it allows the control unit to be small in
size, effecti~ely utilized, and less costly. The
programming unit is used to s-tore in the robot control
unit an operating program, and the robot control unit
operates the industrial robot using the stored
program.
An example of such an improved system is shown
and described in United Kingdom Published Patent
Application 2,0~7,938 A. Therein is described a
j~; 20 teach-assist apparatus for a programmable industrial
robot in which input data representing the positions
of the arm of the robot relative to a stationary work-
piece is inputted during a teaching operation. An
off-line teach-assist computer (reference numeral 34
in Fig. 1 of the Application~ computes path data,
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1 which is stored i.n a control memory of an on-line
control apparatus which directly operates the
manipulator arm. The stored data, which is computed
so that the manipulator arm undergoes the most
efficient movement, also includes projected workpiece
positions in terms of basic linear displacement units,
correspondin~ to possible positions of the workpiece
as it moves down an assembly line. Duxlng work
j operations, the position of the workpiece is
~ 10 continuously determined, and data is selected for
`t operating the manipulator arm in accordance with the
i' detected position of khe workpiece.
, A somewhat similar system is described in Reissue
Uni-ted States Patent 30,016 to Hohn. In that system,
which is shown in block dia.gram form in Fig. 1 of the
Reissue Patent, the data stored in an on-line memory
does not include projected workpiece positions in
terms of basic linear displacement units as in the
case the above-discussed United Kingdom Published
Patent Application. Instead, in response to the
;~ position or the workpiece, feedback signals are
generated which specify the direction and magnitude of
a change in position of the workpiece from its
expected position. The feedback signals are utilized
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1 to modify command signals which are in turn used to
operate the manipulator arm servo mechanism circuit.
Industrial robots in use -today have multiple
functions and are capable of performing not only a
single mo-tion but a variety of different motions.
However, with a conventional external -teaching system,
it has been necessary to store a new program in the
robot control unit each time a different robot
operation is to be performed. For example, if an
industrial robot is being used to supply parts to a
predetermined location and the location -to be supplied
with parts is displaced from a reference position
beyGnd an acceptable range, the industrial robot can
no lonyer accurately perform the desired parts
supplying operatioll. The industrial robot thus needs
to be -tau~ht again, a procedure which is tedious and
time-consuming. Because the programming unit can
store only a single program in the robot control unit,
the robot cannot perform, without reprogramming, all
ZO the many functions of industrial robots. There has
therefore been a need for a robot control unit capable
of storing a plurality of programs and selecting among
them freely.
In practice, it is desirable that the programming
unit be capable of preparing and storing several dozen
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., 1 or more programs, and that the robot control unit be
c capable of storing several different programs semi
permanently.
It is thus an object of the present invention to
provide a robot control apparatus which will meet -the
foregoing requirements and which has a construction
optimum for practical use.
It is a further object of the present invention
to provide a method of easily correcting the
operational positicns of an industrial robot without
correc:tîng the content of a pxogram.
SUMMARY OF TEIE INVENTION
According to the present invention, the above and
o-ther objects are achieved by utilizing an external
robot teaching syskem with a multiplicity of
~ fundamenkal programs stored in a progra~ming unit. A
3 plurality of necessary programs are inputted from the
pxogramming uni-t, subjected to pradetermined
arithmetic operations, and then transferred to a robo-t
control unit. In the robot control unit, a desired
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program is selected and read out of the corresponding
memory for controlling the industrial robot to perform
desired motions.
- Yet further, the invention provides a method for
correctin~ or offsetting a program in a programming
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~ 1 unit and storing the corrected program in a robot
control unit for separately controlling the proyram-
; ming unit and the robot control unit. The programming
unit includes an arithmetic processor for transforming
offset inputs supplied in a Cartesian coordinate
sys-tem to a polar coordinate system for use in a
program stored in the robot control unit. According-
ly, data input operations for industrial robots of a
; polar-coordinate type can easily be performed.
BRIEF DESCRIPTION OF THE DRAWINGS
~i E'ig~ 1 is a block diagram of a first embodiment
of contrvl apparatus for an industrial robot according
to the present invention;
Fig. 2 is a flowchart: for a program preparing
procedure;
:? Fig. 3 is a flowchart for program calling in the
~, program preparing procedure;
r Fig. 4 is a flowchart ~or a storage procedure at
the time of transferring a progxam;
Fig. 5 i5 a block diagram of a second embodiment
of a control apparatus for an industrial robot
according to the present invention used to perform a
method for program correction of the invention; and
Fig. 6 is a flowchart for a program correcting
method of the invention.
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DE S CR I PT I ON OF THE PREFERRED EMBOD I r`lENTS
The present invention will now be descrlbed with
reference to the drawings which illustrate a preferred
embodiment of the invention.
Fig. 1 shows a control apparatus 1 for an
industrial robot according to the present invention.
The control apparatus 1 is composed of an independent
programming unit 2 and a robot control unit 3 which
are interconnected by a detachable communication
cable 4.
The programming unit 2 serves to prepare and
store a number of desired operating pxograms and
d~liver a requested one of the stored operating
programs to the robot control unit 3. The programming
unit 2 includes an input device 5 such as a keyboard
for inputting program data, mode instructions, offset
~positional correction) ~ata, and other inputs; a
program editing arithmetic processor 6 in th~ form of
a CPU (Central Processing Unit) including a control
. 20 unit, an arithmetic unit and a register fox storing
processing programs (which include editing programs,
coordinate transformation formulas, offset processing
programs, and a compiling program for converting
programs to machine language), editing the operating
programs based on input data fro~ the keyboard 5, and
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l performing operations such as coordinate transforma-
tion and conversion in-to machine language; a memory 7
in the form of a RAM (Random Access Memory~ for
temporarily storing data related -to the operating
programs, coordinate transformation formulas, and a
compiling program; an external memory~8 having a large
j storage capacity such as a magnetic tape or a magnetic
disk for storing a multiplicity of edited operating
programs; a display unit 9 for displaying inpu-t and
i 10 stored data; and a communication circuit 10 for
delivering processed (completed~ operating programs
through the program editing arithmetic processor 6 to
the robot control ur.it 3.
~ The robot control unit 3 is speciflcally adapted
to control the opera-tion of an industrial robot 20 of
j the polar~coordinate type. The operation control
~ apparatus 2 is composed of a communication circuit ll
3 for receiving processed operating programs transferred
from the programming apparatus 3; a plurality Or
operating program memories 12, 13, ......... 16 (five
memories in the illustrated embodiment) for storing a
plurality of computed operating programs delivered
. from the communication circuit ll; a selector unit 17
-- for connecting data buses as needed to select writing
3 or reading of the operating programs; a robot
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1 operation contxol unit 18 for generating the slgnals
, which cause the industrial robot 20 to perform the
reql1ired motions; and a mode setting circuit 19 for
setting a desired operation mode for the selector
unit 17 and the robot operation control lmit 18.
Each of the operating program memories 12, 13,
...16 is composed of a RAM and an auxiliary power
, supply or battery which will automatically be con-
3 nected to the RAM upon failure of the commercial power
;;', - 10 source so that the stored content of the RAM will be
protected at all times against accidental erasure.
The selector unit 17 can be controlled by the-
mode setting circuit 19 and also by a detector
~, circuit 21. The detector circuit 21 receives a signal
from an external sensor 22 and operates the selector
unit 17 in accordance with received signal. The
s~nsor 22 may be composed, for example, of a group of
limit switches engagable with dogs attached to an
object handled by the industrial robot 20 for
determining the type of object. The robot operation
control unit 18 has a control circuit 23, an external
input and output control circuit 24, and a robot drive
.? circuit 25.
When the operator selects a continuous operation
. mode using the mode setting circuit 19, the control
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l circuit. 23 enables the selector circui-t 17 to deliver
the stored content of a designated one the operating
program memories 12, 13, ...16, that is, a desired
: operating program is inputted to the robot drive
L. circuit 25. The external input and output control
circuit 24 is responsive to motion~ ~of the robot 20
for detecting its operations and positions with limit
switches, encoders or the like and for delivering data
representative of the operations and positions to the
control circuit 23. The robot drive circuit 25
receives signals from the external input and ou-tput
con-trol circuit 24 based on the content of the
selected operating program and, in response thereto,
confir~s such signals and successlvely sends command
signals to the industrial robot 1 for causing the
desired motions.
Operation of the con~rol apparatus thus
constructed will now be described. The programmer
operates the input device 5 to supply input data such
2~ as operational positions of the industrial robot ~0
. (in Cartesian coordinates and an angular displace~
ment for a chuck) and external input conditions
~ according to a predetermined program preparation
. proc~dure, based on a PTP (Point-To-Point) control
system,~ for example, in which continuous path control
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; 1is carried out. The inputted data is temporarily
stored in the memory 7 through operation of the
program editing arithmetic processer 6 and then stored
in completed form in the external memory 8 at
specified addresses. During this time, the display
; unit 9 displays the stored content or selected
¦ portions thereof. Since the storage capacit~ of the
external memory 8 is large enough to store a number of
programs, it can store as many progr~ms as are
10expected to be needed. When the programming unit 2 is
to deliver an operating program stored in the external
memory 8 to the robot control unit 3, the programming
unit 2 and the robot control unit 3 are interconnected
as an on-line system~ and thereafter a re~uired
operating program is read temporarily from the
external memory 8 into the memory 7 utilizing an inpu-t
program transfer operation. Then, the program editing
arithmetic processer 6 converts th~ content of the
memory 8 into polar coordinates and then into machine
20language through predetermined arithmetic operations.
The data expressed in machine language is fed
through the communication circuit 10 and the com-
munication cable 4 to the communication circuit 11 in
the robot control unit 3. At this time, the robot
control unit is set in an operating program storing
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1 mode by the mode setting ci.rcuit 19, with the selector
unit 17 operated to designate addresses or data
storage. A completed operating program is stored
t through the selector unit 17 into the first operating
program memo.ry 12, for example. In this manner, the
robot control unit 3 can store ~ five operating
programs. Since the program memories 12, 13, ...16
are composed of RAMs as described above, they can
store rewritten data as desired.
Subsequently, the progra~ming unit 2 is
i disconnected from the robot control unit 3, whereupon
the robot control unit 3 can operate independently of
the programming unit 2. The operator can then control
- the mode setting means 1~3 to cause the selector
unit 17 to read a desired operating program out of the
stored content of the operation program memory 16, for
example. Such a program reading instruction can also
be automatica].ly effected by the detector circuit 21
in respon~e to a si~lal from the sensor 22.
The control circuit 23 reads the designated
operating program and, in response thereto, enables
the ro~ot drive circuit 25 to energize a source of
drive for driving the arm of the industrial robot 1.
At the same time, the control circuit 23 receives
signals from the external input and output control
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1 circult 24 indicative of the movement of the
industrial robot 20. The control circuit 23 then
continuously operates the industrial robot 20 under
the control of the selected operating program.
Figs~ 2 through 4 illustrate, respect.ively,
procedures for preparing, calling and kransferring a
program. These procedures will now be described.
After a Start Step 1, it is determined in a
Step 2 if a prograrn is to be prepared. I f a program
is to be prepared, then the keyboard of the input
device 5 is operated to instruct a program preparation
at a Step 3. The programmer feeds various inputs at a
Step 4 while in conversatlon with the memory 7
, according to a predetermined program preparation
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procedure. The inputs include the title of the
t program, the type of the robot, designation of points
i on a plane cobrdinate system, data related to an
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external operation, data indicative of arm movements,
.; and others. These inputs are edited and temporarily
- 20 stored in the m~mory 7. When the programmer calls up
an error check in Step 6 after completion of the data
input operation has been indicated, it is determined
at a Step 7 whether there is an error or not. If
there is any error, then such an error is located at a
Step 8 and corrected at a Step 9. Then, it is
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determined at a Step 10 whether the program data is to
~e transferred, and at a Step 11 whether the program
data is to be stored in -the external memory. If the
program data is to be stored, then the program goes to
; a connector B. If the program da-ta is to be stored in
the external memory 8, then it is ~determlned at a
Step 12 whether the storage medium is a raw
(unrecorded) tape. If it is a raw tape, then a
recording address is designated at a Step 13 and
thereafter a confirmation message is displayed a, a
Step 14. By performing a confirmation instruction at
a Step 15, initialization or recording of an address
zone is per~ormed at a Step 16. IE the storage medium
is not found to be a raw tape in the Step 12, then a
recording position is direc~ly indicated at a Step 17.
`! The progr~n preparation is finished at a Step 19 after
~ the title of the progra~ has been displayed at a
Step 18. The programmer repeats the foregoing opera-
tions as many times as there are programs to be
prepared.
; If no program is to be prepared at the Step 2,
then the program goes to a connector ~ It is then
determined at a Step 20 whether the program is to be
transferred, at a Step 21 whethex there is a magnetic
tape, and at a Step 23 whether a file is to be
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1 checked. If there is no ma~netic tape, then the
program goes to the Step 23 after a cartridge has been
inserted in place at a Step 22. Then, when the
programmer designates a file at a Step 24, the file
can be confirmed by an index display 25. When the
title of the program is indicated a~ a Step 26, the
stored content of the external memory 8 is t~mporarily
read into the memory 7, and the title of the program
is displayed at a Step 27. After it has been deter-
mined at a Step 28 whether the program is to be trans-
ferred, the program goes to the connector B.
When the program reaches the coImector B, that
is, when the program is to be transferred, it is
determined at a Step 30 whether the robot is ready
after the units 2 and 3 have been connected into an
on-line system. If the robot is not ready, then the
power supply status, mode setting and other relevant
parameters in the robot control unit 3 are confirmed
in a Step 31, and the operator effects required
operations at a Step 32. Thereafter, a memory number
in the robot contxol unit 3 is designated at a
Step 33. The program as called is- processed and
transferred in a Step 34, and delivered to a
designated one of the program memories 12, 13, ...16
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l in the robot control unit 3. The program memory 12,
for example, stores the con-tent of the program at a
Step 35. Finally, it is determined at a Step 36
whether there is any error. The procedure is ended at
a Step 37O
Since, according to the present invention, the
programming unit and the `robot control unit are
independent of each other, -the robot control UIlit is
simple in construction and small in size. The
programming unit can be combined with the ro'oot
control unit in an on-line system for storing a
program in an arrangement known as an external robot
teaching system for allowing the programMing unit to
be shared by many xobot control units. While a
program is being stored, there is no need to stop the
operatlon of the industrial robot. Therefore, the
availability of the robot is not reduced. Since the
storage capacity of the robot control unit is large
and there are a plurality of program memories in the
robot control unit, a plurality of programs can be
stored, with the results that the industrial robot has
wider range of use and can perform a sufficient number
of functions. Since the stored data can always be
supplied from the external MemOry, the industrial
robot can readily perform every r~uired motion.
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1 Moreover, with the contents of the programs selected
by the operation of the mode setting means and the
selector unit in the robot control unit, the content
of a required program can be prepared independently of
the programming unit.
A second embodiment of a control apparatus 1 for
an industrial robot of the invention is shown in
Fig. 5, ir. which like reference numbers designate
similar elements in Fig. 1. As in the firs-t described
embodiment, the control apparatus 1 is composed of a
programming unit 30 and a robot control unit 3 which
are constructed as separate units but which can be
connected to each other by a communication cable 4.
The programming unit 30 has a control input
device 35 such as a keyboard having ten numeric keys
and function keys; a temporary memory 6 such as a RAM,
a memory 7 such as a magnetic ~iisk or a magnetic tape;
an arithmetic processor 8 fo:r storing a processing
program and effecting various arithmetic operations
for correc-tion, coordinate transformation, and
conversion into machine language; a co~munication
circuit 10 serving as a transmitter and receiver for
transmitting and receiving programs and data to and
from the robot control unit 37; and a display unit 40
for displaying various data.
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l The robot control unit 3 is constructed in the
same manner as in the embodiment of Fig. 1. Here is
is assumed that the robot control unit 3 is of the
polar coordinate type; that is, it operates using
control data specified in polar coordinate form for
controlling the movements of the industrial robot 3.
In operation, -the programmer operates the con-trol
input device 35 while watching the image displayed by
the display unit 40 to store a desired program in the
temporary memory 36. The stored content in ~he
temporary memory 36 is stored at addresses in the
memory 37 specific for each completed program. A
plurality of programs can thus be stored in the
memory 37 for re~uired operating patterns of movement.
When the program of a particular operating
pattern is to be transferred to the robot control
unit 3, the desired program -is transferred int~ the
temporar~ memory 6 and delivered to the arithmetic
processor 8, in which this program is s~bjected to
coordinate transformation and conversion into machine
language under the con-trol of the processing program.
The resulting program data is supplied through the
communication circuit 10 to the communication
circuit 11. The coordinate transformation is reguired
to transform the data inputted in Cartesian coordinate
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1 form to polar~coordinate form. Such an arithmetic
operation unction for coordinate transformation
permits operational position inputs to be supplied
easily through the inpu-t device without the programmer
having to manually or separately convert the data.
Prior to program transfer, the robot control
unit 3 is set in a transfer mode by the mode setting
circuit 19. The selector 17 may select the memory 13,
for example, for receiving the transferred program.
The content of the program received through the com-
munication circuit 12 is delivered into the memory 13
in which the program is stored. A plurality of
operating pattern programs are similarly stored in the
o-ther memories 1?, 15, ...16.
When it is desired 1:o make a positional
correction or offset due to a change of a rod part,
for example, wi~hout changing the operating pattern,
the mode setting circuit 19 in the robot control
unit 3 is operated to set the latter for a programming
mode. Then, program correction process according to
the pxesent in~ention is carried out as illustrated in
Fig. 6.
After a Start Step 41, the programmer inserts a
magnetic tape cartridge at a Step 42 and designates
the title of a program at a Step 43. Upon such input
1 operation, the designated program is read out of the
memory 37 into the temporary memory 36 in which the
program data is temporarily stored. Simultaneously,
the title of the program is displayed on the display
uni-t a-t a Step 44. Then, it is determined at a
Step 45 whether a positional correction or an offset
is to be made. The programmer supplies an offset-
indicating input at a Step 46 and a correction input
for a corrected position at a St~p 47. As described
above, the correction input can be fed as data
expressed in Cartesian coordinates. X and Y data
which reguires correction of the operational positions
in the operating pattern is pxovided in the form of
difference (delta) inputs.
The data indication of the corrected positions is
temporarily stored in the temporary memory 36 and
displayed on the display unit 40 at the same time.
Since the operating pattern remains unchanged, the
program itself is not changed and only numerical
values used by the program are varied. Subsequently,
it is determined at a Step 48 whether the program is
to be kransferred. If the program is to be
transferred, then the operator connects the
programming unit 3~ and the robot control unit 3
through the communication cable 4 to unite the units 2
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l and 30 as an on-line system at a Step 49. It is then
determined at a Step 50 whether the robot is ready or
not, and thereafter the operator operates the control
input device 35 to designate a storage address in the
robot control unit 3 at a Step 51. ~en the storage
address is designated at the Step 51, the arit~netic
processor 38 corrects the content or data of the given
program" and the corrected data is subjected to
coordinate transformation and converted into machine
language. The corrected program is then transferred
through the communication circuits 10 and 11. The
robot control unit 3 accepts the corrected program and
stores it in the designated memory, for instance, the
memory 13. At this time, it is dete.rmined at a
Step 52 whether there is an error. The corrective
ac'tion is finished at a final Step 53. When the cor-
rected program is read while in an operation mode, the
industrial robot 20 repeats ils motions in a desired
operating pattern at the corrected position based on
~o the data of the corrected program.
While in the for~going embodiment corrected data
is described as being manually supplied through the
control input device 35, such corrected input data can
also automatically be fed by an automatic measuring
device. The automatic measurement can be carried out
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1 by providing a photoelectric sensor at a reference
position, detecting the position of an object to be
worked upon with the photoelectric sensor, and
converting the detected signal into a digital signal
which is supplied -to the temporary memory 36. The
reference position may be selected- outside of the
industrial robot 20 or may it be on the arm o the
industrial robot 20.
With the method of program correction according
to the present invention, no basic operating program
is rec~uired -to be corrected in the program unit, and
only data related to operational positions used in the
operating program need be corrected.- Thus, the basic
program remains unaltered. Any positional correction
can easily be carried out by only partial correction.
The program and data subsequent to correction are
transferred to the robot control unit and stored
therein, so that no arithmetic operation is required
in the robot control unit for correction or offs~t
20 each time a robot movement is effected. Accordingly,
the contrcl sec~uence can be simpli~ied and the robot
operation can be performed at a hi~h speed.
